fix: handle nullable tag in smoke listEndpointsTest

The endpoint is created without a tag, so getTag() returns null on
listed endpoints. Use anyOf(nullValue(), instanceOf(String.class))
instead of a strict instanceOf check.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: smoghe-bw

src/test/java/com/bandwidth/sdk/smoke/EndpointsApiTest.java

@@ -29,6 +29,8 @@
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.CoreMatchers.instanceOf;
 import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.anyOf;
+import static org.hamcrest.CoreMatchers.nullValue;
 import static org.hamcrest.Matchers.is;
 
 import static com.bandwidth.sdk.utils.TestingEnvironmentVariables.*;
@@ -83,7 +85,7 @@ public void listEndpointsTest() throws ApiException {
         assertThat(firstEndpoint.getStatus(), instanceOf(EndpointStatusEnum.class));
         assertThat(firstEndpoint.getCreationTimestamp(), instanceOf(OffsetDateTime.class));
         assertThat(firstEndpoint.getExpirationTimestamp(), instanceOf(OffsetDateTime.class));
-        assertThat(firstEndpoint.getTag(), instanceOf(String.class));
+        assertThat(firstEndpoint.getTag(), anyOf(nullValue(), instanceOf(String.class)));
     }
 
     @Test